Fat and fat-free mass of healthy Swedish children show tracking during early life, but there are differences.

AIM: Obesity may start early in life. We investigated relationships between size and body composition variables in infancy and at 4 years of age using valid estimates of body composition. The results were compared to those obtained when body mass index (BMI) was used to estimate body fatness at 4 years. METHODS: Using air displacement plethysmography, size, fat mass and fat-free mass were studied, between 2007 and 2015, in 253 full-term healthy Swedish children at 1 week, 12 weeks and 4 years of age. RESULTS: Positive associations between variables in infancy and at 4 years were found at 1 and 12 weeks for weight, height, BMI, fat-free mass and fat-free mass index (p ≤ 0.002) and for fat mass, per cent body fat and fat mass index (p ≤ 0.04) at 12 weeks. Fat mass gained during infancy correlated positively (p ≤ 0.031) with per cent fat mass, fat mass index and BMI, all at 4 years. In girls, gains in fat-free mass during infancy correlated with BMI (p = 0.0005) at 4 years. CONCLUSION: The results provide information regarding body composition trajectories during early life and demonstrate limitations of BMI as a proxy for body fatness when relating early weight gain to variables, relevant for later obesity risk.

Longitudinal assessment of body composition in healthy Swedish children from 1 week until 4 years of age.

BACKGROUND/OBJECTIVES: Knowledge of longitudinal body composition development is required to identify the mechanisms behind childhood overweight and obesity and to prevent these conditions. However, accurate data on this development in early childhood are lacking. Our aim was to describe the longitudinal body composition development in healthy young Swedish children. SUBJECTS/METHODS: Body size and composition were assessed in 26 children using air-displacement plethysmography (1 and 12 weeks and 4.4 years of age) and isotope dilution (1.5 and 3 years of age) and compared with available reference data. RESULTS: Body fat (%) for boys (n=16) was 12.8±3.9 (1 week), 25.6±4.8 (12 weeks), 28.2±3.8 (1.5 years), 27.3±5.1 (3 years) and 26.1±3.5 (4.4 years). For girls (n=10) these values were 15.3±2.9, 25.7±3.9, 27.9±3.3, 26.3±7.2 and 26.0±5.3, respectively. These values were above the Fomon reference values at 1.5 years of age and later and higher than the Butte reference (P<0.05) for boys at 1.5 years of age. At all ages the coefficients of variation were higher for body fat (%) (12-30%) than for BMI (4-11%). CONCLUSIONS: At 4 years of age our children had more body fat than indicated by reference data. This high level may have already been established at 1.5 years of age but our small sample and the lack of appropriate reference data limit the possibility of drawing firm conclusions. Our results demonstrate the limitations of BMI when investigating overweight and obesity in early life and highlight the need for appropriate reference body composition data in infants and young children.European Journal of Clinical Nutrition advance online publication, 23 August 2017; doi:10.1038/ejcn.2017.125.

Evaluation of the wrist-worn ActiGraph wGT3x-BT for estimating activity energy expenditure in preschool children.

BACKGROUND/OBJECTIVES: Easy-to-use and accurate methods to assess free-living activity energy expenditure (AEE) in preschool children are required. The aims of this study in healthy preschool children were to (a) evaluate the ability of the wrist-worn ActiGraph wGT3x-BT to predict free-living AEE and (b) assess wear compliance using a 7-day, 24-h protocol. SUBJECTS/METHODS: Participants were 40 Swedish children (5.5±0.2 years) in the Mobile-based intervention intended to stop obesity in preschoolers (MINISTOP) obesity prevention trial. Total energy expenditure (TEE) was assessed using the doubly labeled water method during 14 days. AEE was calculated as (TEEx0.9) minus predicted basal metabolic rate. The ActiGraph accelerometer was worn on the wrist for 7 days and outputs used were mean of the daily and awake filtered vector magnitude (mean VM total and mean VM waking). RESULTS: The ActiGraph was worn for 7 (n=34, 85%), 6 (n=4, 10%), 5 (n=1, 2.5%) and 4 (n=1, 2.5%) days (a valid day was ⩾600 awake minutes). Alone, mean VM total and mean VM waking were able to explain 14% (P=0.009) and 24% (P=0.001) of the variation in AEE, respectively. By incorporating fat and fat-free mass in the models 58% (mean VM total) and 62% (mean VM waking) in the variation of AEE was explained (P<0.001). CONCLUSIONS: The wrist-worn ActiGraph wGT3x-BT in combination with body composition variables explained up to the 62% of the variation in AEE. Given the high wear compliance, the wrist-worn ActiGraph has the potential to provide useful information in studies where physical activity in preschool children is measured.

Strengthening the Reporting of Observational Studies in Epidemiology - nutritional epidemiology (STROBE-nut): An extension of the STROBE statement.

Concerns have been raised about the quality of reporting in nutritional epidemiology. Research reporting guidelines such as the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement can improve quality of reporting in observational studies. Herein, we propose recommendations for reporting nutritional epidemiology and dietary assessment research by extending the STROBE statement into Strengthening the Reporting of Observational Studies in Epidemiology - Nutritional Epidemiology (STROBE-nut). Recommendations for the reporting of nutritional epidemiology and dietary assessment research were developed following a systematic and consultative process, co-ordinated by a multidisciplinary group of 21 experts. Consensus on reporting guidelines was reached through a three-round Delphi consultation process with 53 external experts. In total, 24 recommendations for nutritional epidemiology were added to the STROBE checklist. When used appropriately, reporting guidelines for nutritional epidemiology can contribute to improve reporting of observational studies with a focus on diet and health.

Gestational weight gain according to Institute of Medicine recommendations in relation to infant size and body composition.

BACKGROUND: Intrauterine life may be a critical period for programming childhood obesity; however, there is insufficient knowledge concerning how gestational weight gain (GWG) affects infant fat mass (FM) and fat-free mass (FFM). OBJECTIVES: The aim of this study was to investigate relationships between GWG according to Institute of Medicine (IOM) recommendations and infant size, FM and FFM. We also investigated if the associations were different for normal-weight and overweight/obese women. METHODS: This study included 312 healthy Swedish mother-infant pairs. Infant body composition at 1 week of age was assessed using air-displacement plethysmography. Maternal GWG was defined as below, within or above the 2009 IOM recommendations. Multiple regression analyses were used. RESULTS: Compared with women whose weight gain was within IOM recommendations, women with weight gain below the recommendations had infants that were shorter (-0.7 cm, P = 0.008) when adjusting for confounders. Normal-weight women exceeding IOM recommendations had infants with higher FM (+58 g, P = 0.008) compared with normal-weight women who gained within the recommendations. No corresponding association was observed for overweight/obese women. CONCLUSIONS: Inadequate GWG was associated with shorter infants, while excessive GWG was associated with greater infant FM for women who were of normal weight before pregnancy.

Variation in the fat mass and obesity-related (FTO) genotype is not associated with body fatness in infants, but possibly with their length.

BACKGROUND: Data relating variation at the fat mass and obesity-related (FTO) locus (rs9939609) to fat mass in infancy are inconclusive. OBJECTIVE: To study relationships between FTO genotype and infant size (at 1 and 12 weeks and at 1 year of age) and body composition (at 1 and 12 weeks). METHODS: Body composition was assessed using air displacement plethysmography in 207 infants. FTO was genotyped using the TaqMan assay. RESULTS: The number of risk alleles was related to length at 1 and 12 weeks (P = 0.007-0.033) but not to fat mass. The relationship to length was stronger in boys than in girls. CONCLUSIONS: Our results suggest that the FTO genotype is not related during infancy to fat mass but is related to length in boys but not in girls.

Longitudinal study of the maternal insulin-like growth factor system before, during and after pregnancy in relation to fetal and infant weight.

BACKGROUND: The maternal insulin-like growth factor (IGF) system is considered to be involved in fetal growth regulation. However, available data linking this system to fetal growth are contradictory and incomplete. AIMS: To measure components of the IGF system before, during and after pregnancy in healthy women and to relate these results, and their changes during pregnancy, to fetal weight (gestational week 31) and birth weight. METHODS: Serum concentrations of IGF-I, IGF-II, IGF-binding protein (IGFBP)-1, IGFBP-3 and IGFBP-3 protease activity were assessed in 23 women before conception, at weeks 8, 14, 20, 32 and 35 of pregnancy and 2 weeks postpartum. The data were analyzed using simple and multiple linear regression. RESULTS: One third of the variability in fetal weight was explained by IGF-I in combination with IGFBP-3 protease activity, both assessed at gestational week 32 (p = 0.013). Birth weight was negatively correlated (r = -0.43 to -0.59) with IGFBP-1 at gestational week 20 (p = 0.041), 32 (p = 0.012) and 35 (p = 0.003). CONCLUSION: We propose there is a finely tuned balance among the components of the IGF system, providing a means for fetal growth regulation.

Validation of energy intake by dietary recall against different methods to assess energy expenditure.

OBJECTIVES: To compare the validity of dietary recalls and physical activity recalls and investigate some factors influencing this validity. To provide an example showing how procedures based on recalls of physical activity can assess the validity of dietary recalls and identify subjects constantly underreporting their energy intake (EI). DESIGN AND SUBJECTS: Thirty-seven women were studied using three 24-h dietary recalls, two kinds of physical activity recalls, indirect calorimetry and the doubly labelled water method. RESULTS: The EI obtained using dietary recalls were biased with respect to body mass index (BMI) and attitudes towards body weight and dieting, whereas results obtained using a physical activity recall were not. Eighteen women produced underreports (UR), i.e. their average EI was below 76% of total energy expenditure (TEE), whereas 24 women reported an EI that was lower than TEE on all three recall days, i.e. constantly underreporting subjects. A physical activity recall identified 13 URs and 20 of the constantly underreporting subjects. CONCLUSIONS: In contrast to estimates of EI, TEE assessed using physical activity recalls was not biased with respect to BMI or attitudes towards body weight and dieting. Recalls of physical activity represent potentially useful procedures for identifying URs and constantly underreporting subjects but are not accurate enough for individuals.

Assessment of body fatness in young children using the skinfold technique and BMI vs body water dilution.

OBJECTIVES: To compare body fatness estimated using a skinfold technique and body mass index (BMI) with body fatness estimated using the body water dilution method in healthy Swedish children 9 or 14 months of age. METHODS: Total body fat (TBF) was calculated from total body water, estimated using the doubly labelled water method, and body weight. When expressed in per cent of body weight, these estimates (%TBF-BWD) represented reference values for body fatness. Body fatness was also calculated from skinfold thickness (%TBF-SFT) and as BMI. The children were ranked and grouped into five groups with an increasing level of body fatness using BMI, %TBF-SFT and %TBF-BWD, respectively. SUBJECTS: A total of 30 infants 9 months of age and 29 children 14 months of age. RESULTS: On average, the children (n=59) had a BMI=17.5+/-1.6 kg/m(2) and contained 27.8+/-3.7 %TBF-SFT and 29.1+/-4.4 %TBF-BWD. %TBF-BWD minus %TBF-SFT was=1.35+/-4.06%. By measuring %TBF-SFT or BMI, about 35% of the children could be classified in the correct group with respect to body fatness. Serious misclassification (ie two or more groups too high or too low) was, however, more common for %TBF-SFT (29%) than for BMI (17%). CONCLUSIONS: The capacity of BMI to place children in the correct body fatness group was poor although not quite as poor as the corresponding capacity of the skinfold technique. The latter method produced inaccurate and imprecise estimates of body fatness.

Total energy expenditure, body composition and weight gain in moderately preterm and full-term infants at term postconceptional age.

AIM: To assess total energy expenditure (TEE) and body composition, i.e. total body water (TBW) and adipose tissue volume (ATV), at term age in 8 healthy preterm infants, born between gestational weeks 30 and 33, and in 9 healthy full-term newborns. METHODS: Total and subcutaneous ATVs were assessed using magnetic resonance imaging, while TEE and TBW were estimated using doubly labelled water. RESULTS: Total ATV was 272 +/- 21 and 261 +/- 56 ml/kg body weight, while subcutaneous ATV was 88.9 +/- 1.6 and 89.7 +/- 2.0% of total ATV for preterm and full-term infants, respectively. The corresponding figures for TBW (as percentage of body weight) were 67.4 +/- 2.5 and 68.1 +/- 4.1, respectively. A significant correlation between ATV/kg body weight and body weight was found for full-term (p < 0.0001) but not for preterm infants. TEE for preterm infants was 315 +/- 20 kJ/kg body weight/24 h, which was significantly higher (p < 0.05) than TEE for full-term infants (254 +/- 45 kJ/kg body weight/24 h). At the time of investigation preterm infants weighed significantly (p < 0.05) less (540 g) than full-term infants. After the time of investigation, weight gains of preterm and full-term infants were 38 +/- 12 and 24 +/- 14 g/24 h, respectively. CONCLUSION: When compared to full-term newborns, predominantly breastfed healthy preterm infants at term postconceptional age were significantly smaller, had a similar average proportion of body fat and showed catch-up growth. Their higher TEE/kg body weight can be explained by a higher growth rate and possibly also by higher physical activity.

Total energy expenditure and physical activity level in healthy young Swedish children 9 or 14 months of age.

OBJECTIVES: To measure total energy expenditure (TEE) and total body water (TBW) in healthy Swedish children 9 or 14 months of age. To compare their TEE with current recommendations for energy intake. To define their body composition and relate this to energy expenditure. DESIGN: : Children were investigated at 9 or 14 months. The following variables were measured: TEE and TBW (by the doubly labelled water method), weight and length. Total body fat (TBF), sleeping metabolic rate, activity energy expenditure and physical activity level (PAL) were calculated. SUBJECTS: Thirty infants 9 months of age and 29 children 14 months of age. RESULTS: : TEE was 323+/-38, 322+/-29, 313+/-23 and 331+/-28 kJ/kg/day in 9-month-old girls, 9-month-old boys, 14-month-old girls and 14-month-old boys, respectively. At 9 months of age girls and boys contained 29.6+/-4.8 and 29.7+/-4.5% TBF, respectively. At 14 months the corresponding figures were 29.1+/-4.3 and 28.2+/-4.3%. There was a significant negative relationship between PAL and %TBF (r=-0.81, P<0.001, n=59). CONCLUSIONS: Measured TEE plus calculated energy cost of growth confirm previous estimates that the physiological energy requirements of children 9 and 14 months of age are 15-20% lower than current recommendations for energy intake. One possible interpretation of the relationship between PAL and %TBF is that children with a high TBF content are less physically active than children with less TBF. However, this relationship needs further studies.

[Diagnostic test in clinical nutrition for medical students. Test results show that training in clinical nutrition must be improved]. / Diagnostiskt prov i klinisk nutrition för läkarstuderande. Provresultat visar att utbildningen i klinisk nutrition måste förbättras.

A national core curriculum in clinical nutrition was approved by the Section for Nutrition in the Swedish Society of Medicine in 1995. Here we report on the results of an anonymous diagnostic test based on this core curriculum in clinical nutrition, administered to medical students at the end of medical school. The test was the same for students in Linköping, Lund and Stockholm. Only 42% of the participants obtained an acceptable test result, with the score in Lund being significantly lower than those in Linköping and Stockholm. We compare the results with a similar test administered in Stockholm in 1996, and discuss current developmental work in clinical nutrition being done in all the medical faculties in Sweden.

Electrolytes, water, RNA, total creatine and calculated resting membrane potential in muscle tissue from pregnant women.

BACKGROUND: The nutritional situation of the fetus and pregnant woman is important for human health, but knowledge of how nutrition affects maternal metabolism and physiology during pregnancy is limited. Such knowledge is important, for example in body composition studies, when information about lean tissue composition is needed. Muscle, a main part of lean tissue, changes its composition in response to age and sex, but the effect of pregnancy on this composition is unknown. METHODS: Muscle samples from 11 pregnant and 16 nonpregnant women were analyzed for water, electrolytes, total creatine, alkali-soluble protein (ASP), DNA and RNA. Plasma was analyzed for electrolytes. The amount of extracellular and intracellular water as well as the resting membrane potential (RMP) in muscle were calculated. RESULTS: Pregnant women had lower plasma concentrations of potassium and sodium but higher muscle concentrations of sodium and water (total and extracellular) than nonpregnant women. RMP was more negative in pregnant than in nonpregnant women. Total creatine in muscle (per kilogram ASP) was increased during pregnancy. The muscle content of RNA (per kilogram DNA) was lower in gestational week 18 than in nonpregnant controls. CONCLUSION: Pregnancy influences muscle composition in several ways that are relevant for an increased understanding of interactions between nutrition and reproduction.

Description and evaluation of a method based on magnetic resonance imaging to estimate adipose tissue volume and total body fat in infants.

Information about body fatness is important during nutritional assessment of infants, but current methods to estimate body composition in vivo are often not applicable in infants. Therefore, a new method based on magnetic resonance imaging (MRI) was developed. This method, which can assess the volume and distribution of adipose tissue (AT) as well as total body fat, was applied in 11 healthy full-term infants. Their total body water was also estimated using the isotope dilution technique. Adipose tissue volume (ATV) was calculated from AT area in 16 images of the body taken by an MRI scanner (1.5 tesla). AT area was assessed using a computer program in which AT criteria was defined by the observer. ATV of the infants was therefore evaluated once by three observers and twice by a fourth observer. The different observers estimated total, s.c., and non-s.c. ATV with a precision that varied between 1.9 and 7.2%, 2.0 and 4.8%, and 4.2 and 40.7%, respectively. Variations during AT area calculations accounted for a large part of the imprecision when assessing total and s.c. ATV. The linear relationship between percent total body water and total ATV in relation to body weight was significant in all evaluations. Although average total ATV varied when estimated by the four observers, there was, within each evaluation, a fairly constant order between infants with respect to their ATV. It is concluded that the MRI procedure represents a useful possibility to assess body fatness in infants.

Triglyceride turnover, lipoprotein lipase activity, and fat cell size in adipose tissue of rats during the first 2 weeks of pregnancy.

Understanding the biological function of the fat retained during pregnancy is important when estimating energy needs during reproduction. Women as well as rats are often considered to gain fat at specific anatomical sites during pregnancy and use this fat as a source of energy during lactation. However, mobilized body fat covers only a minor part of the energy needed by the lactating rat dam. In this paper, fat cell size, lipoprotein lipase activity, as well as triglyceride turnover in parametrial and subcutaneous adipose tissues were studied during the first 2 weeks of gestation and in virginal controls to further explore the metabolic and physiological basis for changes in body fat during reproduction in rats. Pregnancy increased the size of parametrial but not of subcutaneous adipocytes. The lipoprotein lipase activity in subcutaneous adipocytes was not increased by pregnancy. The accumulation in adipose tissue of 14C from orally administered 14C-oleic acid was higher in virginal than in pregnant rats. No effect of pregnancy on the rate of lipid turnover in parametrial or subcutaneous adipocytes was found. The findings are in accordance with the contention that body fat gained during rat pregnancy, to a large extent, is a consequence of a general growth of maternal tissues rather than the result of a stimulating effect of pregnancy on fat accumulation by adipocytes from specific body sites.

Changes in total body fat during the human reproductive cycle as assessed by magnetic resonance imaging, body water dilution, and skinfold thickness: a comparison of methods.

Total body fat and fat-free mass were assessed by magnetic resonance imaging (TBFMRI and FFMMRI) in 11-16 healthy Swedish women before pregnancy and 5-10 d and 2, 6, and 12 mo after delivery. On these occasions, TBF was also measured by the body water dilution (TBFBWD) and skinfold-thickness (TBFSFT) techniques. The results were used to compare changes in TBFSFT and TBFBWD during reproduction with changes in TBFMRI. TBFBWD was 1.5-4.0 kg higher than TBFMRI and at all postpartum measurements the difference between these estimates increased significantly with increased body fat content. This difference was also significantly higher 6 mo after delivery than it was 2 and 12 mo postpartum. The possibility that this was due to variations in the degree of hydration of FFM postpartum was considered. TBFSFT was 1.7-3.1 kg higher than TBFMRI and this difference increased with increasing body fat content. The agreement between changes in TBFMRI and TBFSFT was different during different times in the reproductive cycle and was also influenced by the amount of fat lost or gained. The findings thus suggest that there is a risk for bias when changes in TBF during reproduction are estimated by the skinfold-thickness technique as well as by isotope dilution.

Changes in adipose tissue volume and distribution during reproduction in Swedish women as assessed by magnetic resonance imaging.

Adipose tissue volume (ATV; total, subcutaneous, and nonsubcutaneous) was assessed by magnetic resonance imaging in the whole body and in six body compartments of 15 healthy Swedish women before pregnancy and 5-10 d, and 2, 6, and 12 mo postpartum. ATV increased by 5.43 +/- 4.72 L (mean +/- SD) during pregnancy and decreased by 3.18 +/- 4.61 L during the first 6 mo postpartum. The women had more ATV (2.86 +/- 2.32 L) 12 mo after delivery than before pregnancy. Of the ATV gained during pregnancy, 76% was placed subcutaneously and the decrease postpartum was due to a loss of subcutaneous ATV. During pregnancy, 68% of the increased ATV was placed in the trunk and 16% in the thighs. Postpartum fat was mobilized more completely from the thighs than from the trunk. For all variables studied variations between women were large. The results also show that women with a high weight gain during pregnancy retain lean tissue in their bodies.